Carlowrightia arizonica A.Gray

  • Authority

    Daniel, Thomas F. 1983. Carloivrightia (Acanthaceae). Fl. Neotrop. Monogr. 34: 1-116. (Published by NYBG Press)

  • Family

    Acanthaceae

  • Scientific Name

    Carlowrightia arizonica A.Gray

  • Type

    Type. United States. Arizona. Pinal Co.: near Camp Grant, 1867, Palmer 165 (GH!, holotype, photo at DS!).

  • Synonyms

    Carlowrightia cordifolia A.Gray, Justicia alba Sessé & Moc., Carlowrightia glabrata Fernald, Carlowrightia californica Brandegee, Carlowrightia californica var. pallida I.M.Johnst., Carlowrightia mucronata Leonard, Carlowrightia costaricana Leonard

  • Description

    Species Description - Straggling to erect, much branched subshrub to shrub to l(-2) m high, arising from a woody caudex to 20 mm in diameter or a woody rhizome to 5 mm in diameter. Older stems terete and often multistriate or with irregularly fissured bark, 1-5 mm in diameter, pubescent or glabrate. Younger stems green, quadrate to terete, smooth or multistriate, 0.5-2.5 mm in diameter, the pubescence extremely variable (see discussion), the trichomes sparse to dense, evenly disposed or concentrated in 2 vertical, decussate lines, the eglandular trichomes appressed to retrorse to flexuose to curved toward the shoot apex, 0.05-1.00 mm long, the glandular trichomes (if present) 0.05-0.60 mm long, either forming an inconspicuous understory or as conspicuous as the eglandular trichomes, the nodes often more densely pubescent to floccose with tufts of flexuose to erect trichomes to 1 mm long. Leaves reflexed downward to horizontal to strongly ascendent, sessile to petiolate; petioles 0.2-30.0 mm long, pubescent like the younger stems; laminas frequently conduplicate, cordate to lanceolate to ovate to elliptic, 3-120 mm long, 1-65 mm wide (reduced in size acropetally into flower-bearing bracts), mostly (1.0-) 1.3-4.0(-5.0) times longer than wide, acute to rounded to truncate to cordate (often oblique) at base, acuminate to acute to rounded (rarely apiculate) at apex; margins entire (rarely crenulate), flat to slightly revolute, usually ciliate, the trichomes variable; surfaces glabrous or usually pubescent like the younger stems; several orders of venation evident on both surfaces although often obscured on the upper surface of smaller leaves. Inflorescence typically consisting of straight, helicoid, or scorpioid spicate axes or panicles of spicate axes to 25 cm long. Inflorescence axes variously pubescent, usually with a mixture of eglandular and glandular trichomes, the latter either clearly visible (to 0.5 mm long), inconspicuous (0.05 mm long or less), or occasionally absent. Reduced dichasia solitary or opposite at the nodes, sessile in the axils of upper leaves or bracts; flowers 1-3 (or more) per dichasium, each sessile or short (to 0.1 mm long) pedicellate, subtended by 2 bractlets. Bracts sessile, narrowly lanceolate to subulate to triangular, 1-7 mm long, 0.3-2.0 mm wide, usually pubescent like the inflorescence axis. Bractlets narrowly lanceolate to subulate to triangular, 0.9-8.0 mm long, 0.3-1.3 mm wide, pubescent like bracts or often with more conspicuous glands. Calyx 1.5-5.5 mm long, the outer surface pubescent like bractlets or often with more conspicuous glands, the inner surface glabrous or sericeous with appressed trichomes 0.1-0.5 mm long; tube 0.5-2.0 mm long; lobes subulate to triangular, 1.0-4.5 mm long, 0.3-0.8 mm wide at base. Corolla pseudopapilionaceous, white to cream with a papillate, yellow eye fringed with maroon veins on the upper lip (outer surface of the lower-central lobe often yellow), 9-19(-26) mm long, pubescent on the outer surface, especially the lower-central lobe, with trichomes (0.05-) 0.1-0.3 mm long; tube 1.7-8.0(-10.0) mm long, 0.8-1.5(-2.0) mm in diameter; upper lip spatulate, 6.0-12.0(-l6.5) mm long, 2.5-7.0 mm wide, entire to emarginate at apex; lower lip 7-14(-16) mm long, the lateral lobes obovate to oblanceolate-elliptic, 6.5-13.0(-l 5.5) mm long, 2.5-6.0(-7.0) mm wide, the lower lobe conduplicate-keeled, bent upward, 6-11 (-14) mm long, 2.0-5.0(-5.8) mm wide, emarginate at apex. Stamens 4.0-9.0(-10.5) mm long; filaments white, 3.5-8.5 (-9.5) mm long, 0.2-0.4(-0.8) mm wide at base, (glabrous) sparsely pubescent near the base with trichomes 0.05-0.20 mm long; thecae maroon turning black, 0.5-1.9 mm long. Disc 0.2-0.4 mm high. Style 4.0-15.0(-l 8.0) mm long, glabrous. Stigma lobes 0.1-0.3 mm long. Capsule 7.5-14.0 mm long, glabrous; stipe 3-7 mm long; head flattened, 4.5-8.0 mm long (including a terminal beak 1.0-1.5 mm long), 3-5 mm wide; retinacula 1.5-3.1 mm long. Seeds usually 4 per capsule, brown mottled with black to completely black, flat, obliquely cordate in outline, 2.5-6.0 mm long, 2.5-4.5 mm wide, rounded to acute at apex; testa papillose on one or both sides; margins dentate, the teeth usually with retrorse barbs. Flowering. This species has been collected in flower in every month of the year in some portion of its range.

  • Discussion

    Discussion. As circumscribed in this study, C. arizonica is not only the most widely distributed species but the most morphologically variable as well. Due to this variation, it is often difficult to find a suite of characters which will always separate C. arizonica from other species of section Pseudopapilionacea. In general, it may be distinguished from other species of this section by the combination of eglandular or inconspicuously glandular vegetative shoots, eglandular leaves, a large (9-26 mm long), internally white corolla with a papillate, yellow eye fringed with purple veins on the upper lip, glabrous capsules, and seeds with dentate margins. The species did not hybridize successfully with any of the species used in the artificial hybridization program, and although it occurs sympatrically with C. pectinata, no evidence of natural hybridization was found.

    The present treatment is somewhat radical in that it considers several species recognized in recent floras as conspecific with C. arizonica. The arguments for this approach, which have already been discussed (see discussion under Intraspecific Variation and Taxonomic Treatment), are based on the data which follow.

    Figure 24 depicts the variation encountered in 14 specimens of C. arizonica with respect to 6 characters. The character states (proceeding from the center to the periphery of each axis) for each character are: capsule length (8-14 mm), leaf length (5-80 mm), corolla length (9-25 mm), length of the cauline trichomes (0.11.0 mm), calyx length (1-5 mm), and bractlet length (1-6 mm). Based on these and other characters, most specimens of C. arizonica can be grouped into eight forms, each of which is discussed below.

    Form 1. Carlowrightia arizonica was described by Gray based on a Palmer collection from southern Arizona. This plant and other similar individuals have stems with short (0.05-0.20 mm), retrorse to retrorse-appressed, evenly disposed, eglandular trichomes (often with infrequent microscopic glands as well). The laminas are lanceolate to narrowly ovate to elliptic, 3 to 33 mm long and 1 to 9 mm wide. The inflorescence consists of slender, spicate axes with bracts 1 to 3 mm long. The flowers and fruits are small with calyces 1.5 to 3.5 mm long, corollas 9 to 13 mm long, and capsules 7.5 to 10.0 mm long. This form is represented by polygons a and e in Figure 24. These plants occur primarily in the Sonoran Desert of southern Arizona and northern to central Sonora, however three populations of this form have been located in the Chihuahuan Desert (represented by Daniel 330, 636, 964).

    Form 2. Plants closely conforming to polygons b and d in Figure 24 differ from Form 1 by possessing erect to retrorse cauline trichomes (0. l-)0.2 to 0.5 mm long, and inflorescences consisting of stouter, leafy spicate axes with bracts 3.5-7.0 mm long. In addition, the flowers and fruits tend to be larger with calyces (2.5-)3 to 5 mm long, corollas (10-) 12 to 18 mm long, and capsules 9 to 11 mm long. Turner annotated several specimens of this form as "C. arizonica var. hirsuta Happ, ined." The geographic distribution of Form 2 is nearly identical to that of Form 1, the plants occurring in the Sonoran Desert of southern Arizona and Sonora and in the Chihuahuan Desert of western Texas. Populations of Forms 1 and 2 were located within 100 meters of each other in the Tucson Mountains of southern Arizona. Form 1 occurred in a sandy arroyo and Form 2 in the rocky washes leading to the arroyo, however, variation in habitat was noted for each species at other locations. Both forms were visited by the same genus of fly (Lepidanthrax) but artificial hybrids between these forms were not altogether successful. Table VII summarizes the crosses between these forms and the parameters used to calculate the fertility index (I). The F, hybrids are intermediate in characters. Although fruit set, F, germination, pollen viability, and the number of seeds per capsule compare favorably with most intraspecific crosses for other species, the germination of the F2 generation was exceptionally low. It must be pointed out, however, that the percent germination of the control crosses was equally low, indicating either genetic barriers both between and within forms in the F2 generation or improper germination conditions for the F2 generation of these crosses. This latter alternative seems unlikely considering the normal germination of the selfed controls and other intraspecific crosses in Carlowrightia.

    Form 3. Specimens resembling polygons c and n in Figure 24 were described by Gray as C. cordifolia. A Sessé and Mociño specimen (295) labelled "Justicia alba N."" and "Habit. Sinalo."" was annotated by Leonard as C. cordifolia. Examination of fragments and a photograph of the specimen places it within this form. The type locality given for J. alba is not Sinaloa but in the mountains between Tepalcatepec and Coahuayana (i.e. in Michoacán). As the Sinaloa reference is on a separate label attached to the specimen at MA, it is not known whether this specimen is actually the type with an additional (and misleading) label or a specimen collected in Sinaloa. The range of Form 3 extends into Michoacán but other forms are more common in this region and it is possible that the plant originally described as J. alba represents a different form. Plants referred to C. glabrata (Form 6) are especially common in the region and the description of J. alba (e.g. ovate leaves) is probably more applicable to them.

    Plants of Form 3 often resemble plants of Form 1 in pubescence. The cauline trichomes are usually retrorse to retrorse-appressed, eglandular, and 0.05 to 0.20 mm long. They may, however, also be erect to flexuose and 0.2 to 1.0 mm long. In addition, they are not always evenly disposed but can occur in two vertical lines on opposite sides of the stem. Numerous populations exhibiting a variety of pubescence types were encountered during this study. In east-central Sonora, three types of pubescence were noted among plants of this form, all occurring within 10 meters of each other. In some individuals (Daniel 987), all the stems are pubescent with long (to 1 mm), erect to flexuose, evenly disposed trichomes. In other individuals (Daniel 988), the cauline trichomes are short (to 0.2 mm), closely appressed, and evenly disposed giving the stem a pallid appearance. In other individuals (Daniel 989), the trichomes are long (to 0.8 mm), retrorse, and restricted to two vertical lines on opposite sides of the stems. In a nearby locality, plants with short, appressed trichomes (Daniel 977) and plants with the long trichomes disposed in vertical lines (Daniel 978) were encountered occurring with individuals intermediate between these types. In the intermediate plants (Daniel 979, 980), the cauline trichomes are retrorse-appressed, mostly confined to two lines, and vary in length from 0.1 to 0.4 mm.

    The laminas of Form 3 vary from lanceolate to ovate but are most commonly cordate, 6-85 mm long and 2-65 mm wide. The inflorescences and calyces are similar to those of Form 1, but the latter are often conspicuously glandular. The corolla varies from 12 to 18 mm in length and the capsular length varies from 10.0 to 13.5 mm. In this form, the margins of the seeds are often concave. Plants of Form 3 range from central Sonora and southwestern Chihuahua south to Guerrero; however, they tend to be more common in Sonora and Sinaloa. Although Form 3 resembles a possible less xeric version of Form 1, indeed plants of Daniel 962 (Form 3) grown from seed in a common garden greatly resemble plants of Daniel 203 and Daniel 330 (Form 1), attempts to hybridize these forms were not successful. Although 100% capsule formation was observed for eight crosses, none of the 20 seeds planted germinated. Attempts to hybridize Forms 2 and 3 were similarly unsuccessful as all of the 21 seeds planted failed to germinate. In limited crosses between individuals of Form 3 (Daniel 962 and Daniel 1029), three of seven attempted crosses (43%) set fruit and all 10 seeds planted germinated.

    Form 4. Plants similar to polygon 1 in Figure 25 were described as C. californica, although the validity of the distinctions between C. californica and C. cordifolia was questioned by Johnston (1924) and Standley (1926). Wiggins (1964, 1980) separated them on the basis of the types of pubescence on the leaves and inflorescence axes. The cauline pubescence is usually dense and either evenly disposed or concentrated in two lines on opposite sides of the stem. The trichomes are either eglandular, retrorse, appressed, and 0.05 to 0.10(-0.20) mm long, or eglandular, retrorse to flexuose, and 0.2 to 0.8 mm long with an understory of glands 0.1 to 0.2 mm long (or the glands lacking). The laminas vary from ovate to cordate and are 10 to 60 mm long and 4 to 38 mm wide. The inflorescence consists of erect to nodding, stout, usually unbranched (or with branching confined to the base), glandular (rarely eglandular) spicate axes with bracts 2.0 to 4.5 mm long. The calyx varies from 2.8 to 5.0 mm in length; the corolla varies from 12 to 19 mm; and the capsule varies from 10 to 14 mm. There is considerable variation in the pubescence of the stem and inflorescence axis but there are intermediate types between the extremes. Plants of Form 4 are concentrated in Baja California; however, plants resembling this form occur in southern Sonora and northern Sinaloa.

    Johnston described C. californica var. pallida based on material from San Esteban Island in the Gulf of California. These plants differ from typical C. californica by their extremely pallid-canescent stems with dense, closely appressed trichomes to 0.3 mm long. Although the type material is scanty, lacking leaves and flowers, collections identical in form to it were made during this study (Daniel 207, 209) from the Bahia Concepci6n region of eastern Baja California Sur. Both Johnston’s specimens collected in April and my collections in June are nearly or completely leafless. However seeds of Daniel 207 were subsequently grown in the greenhouse and these unusual plants can now be more fully characterized. The leaves are petiolate and the laminas are lanceolate to ovate, to 20 mm long and to 10 mm wide. The inflorescence consists of numerous, conspicuously glandular spicate axes. The corollas are a creamy color with a yellow eye fringed in purple on the upper lip. Considering the variation in pubescence in other individuals of Form 4, and because these specimens are distinguishable only by their cauline pubescence, they are treated here.

    Form 5. Another form from Baja California, represented by polygon m in Figure 25, consists of plants differing from Form 4 by the presence of conspicuous glands (0.2-0.6 mm long) on the vegetative stems. In addition, the inflorescence of these plants is lax, consisting of a much-branched panicle of weak spicate axes.

    Within Form 5, two minor variants in pubescence are worthy of note. Jones collected specimens (24170, 24200) in southern Baja California Sur which frequently have long (0.5-1.0 mm), flexuose trichomes on the inflorescence axes and the eglandular pubescence of the vegetative stems is sometimes recurved and disposed in two lines. However in these characters there is considerable overlap with other specimens of Form 5. The cauline pubescence of a series of specimens from Cerralvo Island (Moran 3573, 9458; Johnston 4052) consists of eglandular, retrorse-appressed trichomes 0.05 to 0.20 mm long. They lack both the long, flexuose eglandular and stipitate glandular trichomes usually found in Form 5, but in other characters they are identical with most of the specimens of this form. Plants of Form 5 appear to be restricted to southern Baja California Sur.

    Form 6. Plants similar to polygons g and j in Figure 25 have been described as C. glabrata Fernald, C. mucronata Leonard, C. coyucana Leonard, and C. costaricana Leonard. In these plants, the vegetative stems are variably pubescent, the trichomes nearly appressed to flexuose, ranging in length from 0.2 to 1.0 mm, and evenly distributed or disposed in two lines, but are always eglandular. The laminas are ovate to lanceolate, (10-) 13 to 120 mm long and (2-)5 to 60 mm wide. The inflorescence consists of lax, slender spicate axes lacking conspicuous glands and has bracts 1 to 2 mm long. The calyx is 1.5 to 3.0 mm long and is pubescent with a mixture of eglandular and glandular trichomes. The corolla varies from 9 to 19 mm in length and the capsule is between 8 and 14 mm long. These plants range throughout western Mexico from central Sinaloa south to Oaxaca and into northwestern Costa Rica.

    Fernald described C. glabrata from collections of Palmer (892) and Lamb (420). The lectotype is here designated as Lamb’s specimen at GH. Leonard’s descriptions of C. coyucana and C. mucronata from Hinton’s collections in western Guerrero were based on single collections. Leonard noted the similarities between C. mucronata and C. glabrata but distinguished the former by its longer capsule, larger seeds, and calyx pubescence which consists of long, eglandular trichomes and short glands. None of these characters holds up when the variation in a large number of specimens referable to C. glabrata is examined. Carlowrightia coyucana was described from scant, apparently heavily grazed material, which may account for the small laminar size (to 15 mm long). In the totality of its characters, it cannot be considered distinct from specimens commonly referred to C. glabrata. In his description of C. costaricana, Leonard noted the similarity of this species to C. glabrata, the differences being the minutely puberulent rather than pilose rachises, smaller leaf blades, and larger capsules of the former taxon. The corolla of C. costaricana is reported by Leonard to be "purplish (?)," although no information concerning the corolla color is provided on Standley and Valerio’s type collection, presumably because the dry corolla has a purplish cast (Leonard described the corolla of C. mucronata in a similar fashion). Other collections of C. arizonica reported or observed to have a white corolla show the same purple coloration after drying, and field observations of C. arizonica reveal that the corollas of many individuals are purplish on the outer surface of those parts exposed in bud. Data on Standley's collection 74521 from Guatemala note a purple corolla and Gibson (1974) likewise describes the corolla of C. costaricana. Although I have not seen fresh material of this form from Central America, I believe that it has a white to cream-colored corolla with a yellow eye bordered by radiating purple veins on the upper lip as in other regions. A similar, confusing situation concerning the corolla color of Palmer’s type specimen of C. arizonica was discussed by Henrickson and Daniel (1979). The variation described for C. costaricana falls well into the range of variation of specimens of C. arizonica.

    In limited crosses between Forms 6 and 2, two out of four (50%) attempted crosses set fruit and none of the six seeds planted germinated.

    Form 7. Plants apparently restricted to a limited arid region of central Guerrero known as Zopilote Canyon are represented by polygon i in Figure 25. In these individuals the cauline pubescence consists of flexuose to appressed, eglandular trichomes 0.2 to 0.7 mm long. These are either evenly disposed or arranged in two vertical lines. The laminas are similar to those of Form 6 but are much thicker in texture. The inflorescence axes are also similar to those of the preceding form but are stouter and the bracts range in length from 3 to 5 mm. The calyx is 3 to 5 mm long and the corolla varies from 18 to 26 mm in length. The capsules are similar to those of Form 6. This form as well as the preceding one occur sympatrically in Zopilote Canyon.

    Form 8. Four collections from southern Mexico (Carlson 3028, Cavender s.n., MacDougall s.n., and McVaugh 22197) differ from other members of C. arizonica by their cauline pubescence which is mostly curved toward the shoot apex. Cavender’s specimen is represented by polygon f in Figure 25. In these individuals, the cauline pubescence is eglandular and restricted to two opposite, decussate lines, the dichasia are borne along only one side of the inflorescence axes, and the inflorescence axes are pubescent with an understory of glandular trichomes less than 0.1 mm long and an overstory of either flexuose to recurved eglandular trichomes 0.5-1.0 mm long or glandular trichomes 0.1-0.3 mm long. In addition, the stipe of the capsule is often considerably shorter than the head. McVaugh’s collection was made in the vicinity of Zopilote Canyon in Guerrero, where Form 7 occurs, and was taken with another specimen of C. arizonica (McVaugh 22200) which resembles Form 3.

    Because those forms grown in a common garden maintain their distinctions, the differences appear to be genetically fixed. The inability of several of these forms to hybridize with one another indicates that the genetic differences between them may be considerable. However due to the sympatry observed between several forms and the general overlap in most characters, they are not accorded formal taxonomic status. Indeed numerous individuals do not fit well into any of the forms described here and others tend to bridge morphological gaps between forms. A more precise definition of the C. arizonica complex may result from an extensive study utilizing cytogenetics and phytochemistry.

    Distribution and Ecology: Carlowrightia arizonica is the most widely distributed species of the genus, ranging from southern Arizona to the state of Guanacaste in Costa Rica (Fig. 23). The species is especially common in the cape region of Baja California, in the coastal lowlands of western Mexico, on the western escarpment of the Sierra Madre Occidental, and on the southern escarpment of the Sierra Madre del Sur. It is less common to the southeast of the Sierra Madre del Sur. It also occurs in the Chihuahuan Desert of western Texas, Chihuahua, Coahuila, and San Luis Potosi where its occurrence is very sporadic. The species grows in a variety of habitats, but is most frequently encountered in rocky or sandy washes and arroyos, on rocky ledges or hillsides, an in roadside ditches at elevations from sea level to 1400 meters. In the northern portion of its range, C. arizonica is found in desert scrub and semi-arid forest associations with species of Larrea, Olneya, Cercidium, Opuntia, Prosopis, Carnegiea, Franseria, Fouquieria,Bursera, Jatropha, Lysiloma, Pachycereus, Acacia, Randia, Quercus, Dodonaea, Lemaireocereus, Tecoma, Mimosa, and Celtis. In the Acacia-plains of east-central Sonora, C. arizonica often becomes a dominant understory plant. Further south, the species occurs in dense subtropical to tropical, subdeciduous to deciduous forests with species of Cordia, Caesalpinia, Juliania, Bursera, Acacia, Cyrtocarpa, Pseudosmodingium, Brosimum, Cephalocereus, Cassia, Tabebuia, Astronium, Hura, Jacaratia, and Trichilia.

  • Distribution

    United States of America North America| Arizona United States of America North America| Texas United States of America North America| Baja California Mexico North America| Chihuahua Mexico North America| Chiapas Mexico North America| Coahuila Mexico North America| Colima Mexico North America| Guerrero Mexico North America| Jalisco Mexico North America| México Mexico North America| Michoacán Mexico North America| Nayarit Mexico North America| Oaxaca Mexico North America| Puebla Mexico North America| San Luis Potosí Mexico North America| Sinaloa Mexico North America|